1. Field of the Invention
The present invention relates to a device for arranging random works. More particularly, the present invention relates to a device in which one robot is provided with a plurality of arms to arrange various works randomly conveyed and carry out the arranged works to a subsequent step.
2. Description of the Related Art
Conventionally, products (hereinafter referred to as xe2x80x9cworksxe2x80x9d) such as tubes, bottles and caps used as containers of chemicals or cosmetics are generally arranged to have a predetermined posture so that packing of them in boxes and attachment of labels to them can be easily carried out.
More specifically, since a large quantity of works are formed and supplied in a disorderly manner, i.e., at random, they are arranged by a device named xe2x80x9ca part feederxe2x80x9d and then transferred to a subsequent step. The part feeder is intended to basically handle only one type of works and is a device with a comparatively simple mechanism that is designed and manufactured according to a required processing ability each time. For this reason, a sufficiently high processing ability cannot be achieved and the change of the type of works is inadequately dealt with. When plural types of works need to be handled, time required for set up becomes correspondingly longer, which results in low productivity.
Particularly when plural types of works need to be handled or a high processing ability is demanded, a method for arranging works by using a robot comprising an image processing device (vision) is conventionally used. In this method, specifically, a vision sensor such as a CCD (charge coupled device) camera is adapted to capture information pertaining to a position or posture of each work and the arm of the robot is controlled according to this information to arrange the works. This method is advantageous in that the mere switching of an operation program according to the change of the type of works makes it possible to handle various types of works and the time required for set up can be thereby reduced.
In a comparatively simple work operation such as an arranging operation, since there is little difference between the processing ability of the conventional general-purpose robot and the processing ability of the part feeder, the number of robots is increased when a higher processing ability is demanded. In this case, a plurality of robots each comprising the robot controller, the arm, and the image processing device are totally controlled by using a total control board that also controls peripheral devices such as a conveyor for conveying works to thereby carry out a work operation (see Japanese Patent Application Publication No. Hei. 7-281721 and Japanese Patent No. 2717771). These references disclose systems in which the image processing device is not essential.
However, the method for improving the processing ability by increasing the number of the robots makes a system complicated and causes degraded cost-performance. The too complicated system for dealing with the comparatively simple work operation such as arrangement of works has resulted in obstructions to the improvement in the processing ability.
The present invention has been developed for the purpose of obviating the aforesaid problem of the prior art, and an object of the present invention is to provide an improved device capable of simplifying a system and thereby improving a processing ability greatly when the robot performs a comparatively simple work operation such as transfer of works and when various types of works randomly conveyed are arranged and carried out to a subsequent step by using the robot.
In accordance with the present invention, there is provided a random work arranging device that arranges randomly conveyed works by using a robot and carries out the arranged works, wherein the robot comprises a plurality of arms and a single robot controller for controlling respective arms independently one another to arrange and transfer the works from a conveying position to a carry-out position.
In the arranging device, the robot of the arranging device arranges and transfers the works from the conveying position to the carry-out position according to a signal from a position sensor for detecting a conveying position of a conveying mechanism for conveying the work and a signal from a vision sensor for detecting a position, posture, and/or shape of the work conveyed by the conveying mechanism.
Preferably, the work which has not been carried out is returned to a conveying starting point.
Preferably, the work is made to have a desired posture while it is transferred by each of the arms.
Preferably, each of the arms is specified to transfer a specific work.
Preferably, when deciding that there is a work that cannot be transferred by arms, an arm is specified to transfer a work situated upstream from the work that cannot be transferred.
Preferably, the work is prevented from rolling while it is conveyed.
Preferably, protrusions are provided on a surface of a conveying belt of the conveying mechanism such that they are arranged in a predetermined configuration. In this case, more preferably, the conveying belt including the protrusions is transparent.
Preferably, the arranging device comprises a light path changing means for changing a light path of light transmitted through the conveying belt. In this case, more preferably, the light path changing means is a mirror provided at a predetermined angle at a predetermined position above the conveying belt and an angle of the mirror is adjustable.
Preferably, the arranging device comprises an image processing means for recognizing a transparent work in a transparent work recognition process.
Preferably, the arranging device comprises a shape check unit for checking a shape of a work based on image data from the image processing means. In this case, an outer shape of the work is checked, the outer shape is checked based on various amounts of outer characteristics of the work, or the outer shape is checked based on specific information of a specific portion of the work.
Preferably, the arranging device comprises a defective discarding mechanism for discarding a work that has been judged defective in a check process performed by the shape check unit.
Preferably, each arm is constituted by three axes, two of which are controlled by the robot controller as axes of the robot. Each arm may be constituted by two axes, one of which may be controlled by the robot controller as an axis of the robot. In this case, an axis other than the axis controlled by the robot controller is controlled by the same as a peripheral device. Each arm may be constituted by three axes which are controlled by the robot controller by the axes of the robot. Each arm may be constituted by two axes which are controlled by the robot controller as the axes of the robot.
The robot controller of the arranging device comprises a peripheral device control unit for controlling a peripheral device such as a conveying mechanism including a conveying belt and a camera, a conveyor position detecting unit for detecting a position of the conveying belt; a work position detecting unit for detecting a position, posture and/or shape of each work based on image data generated by the image processing unit; a picking position computing unit for computing a position at which each work is to be picked on a carry-in conveyor for each arm based on information detected by the conveyor position detecting unit and the work position detecting unit; an allocation operation unit for specifying an arm among the arms to pick a specific work based on the information computed by the picking position computing unit and according to a predetermined allocation algorithm; and an arm control unit for controlling each arm to arrange the work on the carry-in conveyor according to an operation result by the allocation operation unit and the information computed by the picking position computing unit.
As should be appreciated, the structure of the arranging device that arranges works conveyed randomly and carries out the arranged works can be simplified and its processing ability can be greatly improved.
For instance, for a comparatively simple work operation, two axes of each arm constituted by three axes are controlled by the robot controller as the axes of the robot. Because the number of arms that can be controlled by a single robot controller is increased, the processing ability of one robot can be improved. The simplified structure of each arm brings about its high-speed operation and further improves the processing ability.
Depending on the type of a work operation, each arm is adapted to have two axes, one of which is controlled by the axis of the robot. In this case, since only the operation of the axis is controlled by the robot controller as the axis of the robot and the number of arms that can be controlled by a single robot controller can be thereby increased, the processing ability of one robot can be further improved. Also, the structure of the arms can be further simplified and the processing ability ca be improved with ease.
According to a preferred embodiment of the present invention, the transparent works and non-transparent works may coexist when conveyed. Therefore, time required for set up is reduced and further improved processing ability is achieved.
According to another preferred embodiment of the present invention, the works are prevented from rolling while they are conveyed. Because spherical works or cylindrical works can be processed like other works, the time required for set up is reduced and the processing ability can be further improved.
According to still another preferred embodiment of the present invention, the shape of the work is checked while it is conveyed. So, the shape check of the work in a subsequent steps can be dispensed with, and the steps and equipment can be simplified.
According to a further preferred embodiment of the present invention, the work that has been judged defective in a shape check process is discarded. The defective work is prevented from being conveyed to a subsequent step and the processing ability can be further improved.
This object, as well as other objects, features and advantages of the invention will become more apparent to those skilled in the art from the following description taken with reference to the accompanying drawings.